On surfaces of semiconductor wafers, glass substrates for liquid crystal display device, or the like, minute circuitry patters are formed by a photolithography step and an etching step. In the photolithography step, a chemical liquid supplying apparatus is used to apply chemical liquid such as photoresist liquid onto the surfaces of the wafers or glass substrates, and the chemical liquid accommodated in a container is sucked up by a pump and passes a filter and the like to be applied onto applied materials such as wafers by a nozzle. Patent Document 1 (Japanese Patent Application Laid-Open Publication No. 2000-12449) discloses a processing liquid supplying apparatus for supplying wafer photoresist liquid, and Patent Document 2 (Japanese Patent Application Laid-Open Publication No. 2004-50026) discloses a coating apparatus for supplying photoresist liquid onto glass substrates for liquid crystal display device.
In such a chemical liquid supplying apparatus, when particles such as dust coexist in the applied chemical liquid, they adhere to the applied materials and cause a pattern defect, whereby a yield of products is decreased. When the chemical liquid in the container accumulates in the pump, it is changed in quality, and the chemical liquid changed in quality becomes particles in some cases. Therefore, it has been demanded that the chemical liquid is not accumulated in the pump that discharges the chemical liquid.
Used as the pump that discharges the chemical liquid is a pump, in which a pump chamber into which the chemical liquid flows and a drive chamber that expands and contracts the pump chamber are partitioned by a partition film such an elastically deformable diaphragm or tube. Indirect liquid, i.e., an incompressible medium is filled with the drive chamber, whereby the chemical liquid is intended to be pressurized via the partition film. A pressurization method of the incompressible medium includes a bellows type as described in Patent Document 3 (Japanese Patent Application Laid-Open Publication No. 10-61558), and a syringe type of using a piston as shown in Patent Document 4 (U.S. Pat. No. 5,167,837).
A reciprocating pump for discharging liquefied gas includes, as described in Patent document 5 (Japanese Patent Application Laid-Open Publication No. 2006-144741), a type of using a bellows to seal fluid in the piston from the outside.